The drop in value of the British pound against the dollar has prompted a joke making the rounds among currency traders, I gather from the July 18 issue of Bloomberg BusinessWeek: “Boris and Nigel talked voters into leaving the European Union, and now cable is so low you’ll trip over it if you aren’t careful.”

Huh?

Cable is currency traders’ slang for the exchange rate between the British pound and the US dollar: the first two currencies for which prices were updated via transatlantic cable – starting around 1866.

Note that it’s just “cable,” not “the cable.” That should tip you off. The thing you might literally trip over would be “a cable” or “the cable.”

And cable is not interchangeable with “pound.” “It’s specifically the price of the pound in dollars,” BusinessWeek said. “Anyone who uses terms like ‘Cable-yen’ or ‘euro-cable’ is to be dismissed as an amateur,” one guide to “forex jargon” notes sternly. Forex jargon – currency traders’ lingo – has traditionally drawn heavily on Cockney rhyming slang, plus terms borrowed from bookmakers and other casual abbreviations, such as “yard” (for “billion”), from the French milliard.

In this world, the sentence “The Old Lady just bought half a yard of cable and there are plenty of bids for Bill and Ben” makes perfect sense.

Translation: The Bank of England (the Old Lady of Threadneedle Street) just bought half a billion dollars’ worth of sterling, and there’s interest in buying Japanese yen – “Bill and Ben” is rhyming slang for yen. (The original “Bill and Ben” were puppets in a popular children’s TV series during the 1950s. It doesn’t “mean” anything. It just rhymes.)

This colorful lingo is on the way out, though. For one thing, there are fewer Cockneys around. Traders’ demographics are shifting. As Nia Williams reported for Reuters a few years ago, currency traders nowadays are often graduates of top universities. Time was, though, when lads with little formal education could start in a back office and work their way up to making a fortune.

“They were the ‘barrow boys’ coming off the market stalls,” as one trader told Ms. Williams – vendors selling fruit or vegetables out of handcarts. “It was more working class and with that came the language of the street.” Some dealers in those days – 30 years ago – owned produce and flower stalls, too.

Technology has wrought changes as well, as in almost every field, it seems, where the focus has shifted from real things – whether quid or quinces – to data on screens. Electronic trading has largely supplanted cheerful banter over the telephone.

A trader in another branch of finance, in his early 30s, whom I talked with recently, noted that over the past year or so, the last vestiges of “open outcry,” or face-to-face trading, had pretty much disappeared from his own field.

Was I imagining things, or did I hear a note of wistfulness in his voice as he said this?